Hi Lars,
I have two suggestions:
- `xargs` almost always present and it can run in parallel (-P) but script needs to be changed:
for((i=1;i<=28;i++)); do echo "SELECT find_overlap_gap_single_cell('test_data.overlap_gap_input_t1','geom',4258,'test_data.overlap_gap_input_t1_res',${I},28);"; done | xargs -n1 -P 10 psql ...
- `UNION ALL` might trigger parallel execution (you need to mess with the cost of the function and perhaps other settings):
SELECT find_overlap_gap_single_cell('test_data.overlap_gap_input_t1','geom',4258,'test_data.overlap_gap_input_t1_res',1,28)
UNION ALL
SELECT find_overlap_gap_single_cell('test_data.overlap_gap_input_t1','geom',4258,'test_data.overlap_gap_input_t1_res',2,28)
...
Cheers,
On Thu, 5 Dec 2019 at 23:11, Lars Aksel Opsahl <Lars.Opsahl@xxxxxxxx> wrote:
Hi
I have a function that prepares data, so the big job can be run it in parallel.
Today I have solved this by using "Gnu parallel" like this.psql testdb -c"\! psql -t -q -o /tmp/run_cmd.sql testdb -c\"SELECT find_overlap_gap_make_run_cmd('sl_lop.overlap_gap_input_t1','geom',4258,'sl_lop.overlap_gap_input_t1_res',50);\"; parallel -j 4 psql testdb -c :::: /tmp/run_cmd.sql" 2>> /tmp/analyze.log;
The problem here is that I depend on external code which may not be installed.
Since Postgres now supports parallel I was wondering if it's easy to trigger parallel dynamically created SQL calls.
If you look at https://github.com/larsop/find-overlap-and-gap/blob/master/src/test/sql/regress/find_overlap_and_gap.sql you see thatfind_overlap_gap_make_run_cmd generates as set of 28 sql calls.
So is it in a simple way possible to use Postgres parallel functionality to call this 28 functions i parallel so I don't have dependent on externally install programs ?
When this 28 sql calls are done, the find_overlap_gap_make_run_cmd may continue to the next step of work. So the function that triggers parallel calls wait for them complete and then may start on the next step of work.
Thanks .
Lars
Ondrej
